GBT02A-049

Exploration Of Millisecond Pulsar Timing Stability

Abstract

Precision timing of an array of millisecond pulsars (MSPs) is the only experimental tool for the direct detection of gravitational radiation on time scales of years. Kaspi et al. (1994 ApJ, 428, 713) conducted a pioneering precision timing study at Arecibo with two nearby pulsars, B1855+09 and B1937+21, and placed an upper limit of 6 x 10**-8 on the energy density of nHz gravitational radiation in the Universe. With the precision timing of newly discovered millisecond pulsars, the development of new data acquisition systems and longer timing data sets, this energy density limit will be improved by two orders of magnitude, or we will have a detection! The primary source of gravitational radiation is a stochastic background from the Universe of coalescing Massive Black Holes. With this proposal we will begin timing a number of MSPs for the purpose of including the GBT in the sites most valuable to the Pulsar Timing Array goals discussed above. Some of the pulsars here will prove to be excellent for continued regular observing, some will not. This first round proposal will be for the express purpose of determining which pulsars deserve continued observation. We discuss a number of sources of systematic error that we will study in the proposed exploration of new pulsars for the Pulsar Timing Array. Our plan is to spend about 18 minutes at each of 3 radio frequencies per pulsar for 11 pulsars on each of 2 days for 3 separate epochs during the trimester. The three frequencies will be one band within a single Prime Focus receiver and bands at Lband (1.4 GHz) and Sband (2.4 GHz). On the two days of an epoch we would use a different PF receivers, PF 1-2 (0.38-0.52GHz) and PF 1-4 (0.68-0.92 GHz). The overall goal for the proposal will be 3-6 samplings at a given band. Profile integrations of approximately 3 minutes will allow ``timeability'' to be assessed by comparing internal error propagation to single epoch RMS timing residuals and then multi epoch residuals. And this will be carried out as a function of frequency as well. These observations will provide essential groundwork for a multi-year monitoring program as well as a self-contained study.

**Investigators**
Name	Other *	Institution	Email	Phone
Don Backer	PI	University of California	dbacker@astro.berkeley.edu	510-642-5128
Ingrid Stairs		NRAO - Green Bank	istairs@nrao.edu	(304)456-2213
David Nice		Princeton University	dnice@princeton.edu	(609)258-6347
Andrea Lommen		University of California, Berkeley	alommen@astro.berkeley.edu	510-642-5275

* PI = Principal Investigator; T = Thesis observations; S = Student

Front Ends

Prime Focus 1-4  8(0.68 to 0.92 GHz)
Prime Focus 1-2  4(0.385 to 0.520 GHz)
Gregorian L(1.15 to 1.73 GHz)
Gregorian S(1.73 to 2.6 GHz)

Back Ends

Coherent Green Bank-Berkley Pulsar Processor
Berkley Caltech Pulsar Machine

Type of Observing

Point Source
Continuum
Monitor
Circular Polarization
Pulsar
High Time Resolution

Switching Type

Allocated time: 72.00 hours.

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